Wound filter



June 1966 J. H. GOLDMAN ETAL 3,255,839

WOUND FILTER Filed April 10, 1961 4 FIG.| Z4 FIG.3

INVENTORS JOSHUA H. GOLDMAN PHILIP E. ASHITON fro.

United States Patent 3,255,889 WUUND FILTER Joshua H. Goldman, Hadlyme, and Philip E. Ashton, Meriden, Conn, assignors to American Machine & Foundry Company, a corporation of New Jersey Filed Apr. 10, 1961, Ser. No. 102,008 4 Claims. (Cl. 210-457) This invention relates to filters and fluids and, in par-. ticular, to the wire mesh or foraminous cores on which strand or roving material may be wound.

Filters of this type, to which the present invention is addressed, are shown in US. Patents 1,751,000, 2,028,061 and Re. 22,651. The co-pending application S.N. 731,682 (now US. Patent No. 3,065,856 issued Nov. 27, 1962) of J. H. Goldman, a co-inventor in this present case, also shows a core. The patents and the application mentioned disclose filter elements comprising a body of strand material wound axially to and fro under tension onto a substantially cylindrical foraminous core in a series of carefully arranged right and left hand helices designed to place successive courses in register one over the other to form a regular series of tubular openings running more or less radially from the core to the external surface of the filter body. These openings provide filtering passages for the fluid being processed.

The ends of these filter elements are preferably in the form of plane discs which may be readily sealed, without cross leakage and without deformation of the filtering passages by pressure on said ends in an axial direction against sealing surfaces, plane or otherwise, within the filter housing in which the elements are used. The Goldman Patent 2,028,061 shows one form of seal in FIG. 3; another and widely used form of seal is shown in U.S. Patent 2,525,287 to Cuno. In addition, it is common practice to stack elements one on the other in which case they may afford mutually contacting sealing surfaces.

A common difliculty encountered in manufacturing filter elements of the type mentioned is the tendency of the first few layers of strand material to slip axially of the core at the point of reversal in its movement to and The failure of the courses to register one over the other near the ends causes some of the filtering passages to be distorted and frequently to be closed. It also results in an uncontrollable departure of the ends from the desired plane formation and a varying firmness of structure. These effects are detrimental to sealing and may encourage severe axial deformation of the element when sealing pressure is applied. If the winding tension is minimized to reduce the axial drag" on the strand at the point of traverse reversal the resulting element is frequently soft and easily damaged. If the tension is increased to obtain a firm element the resulting increase in drag will enhance the tendency of the first few layers to slip at the point of traverse reversal. There is a further difliculty in that a change of 'type of core, say from a soldered wire mesh to a smoothly perforated bright tinned sheet steel core, will change the grip of the strand on the core and require extensive re-adjustment of winding tension.

The problem here discussed has long been recognized by those skilled in the art and one solution has been attempted by modifying the cams which affect the axial traverse to include a dwell at the point of reversal. Other attempted solutions have comprehended cyclic changes in the winding tension. While these solutions may result in improvements in the art, they involve mechanical modification of high speed machines and, in general, tend to treat a symptom instead of correcting the basic fault which is inadequate grip between the strand and the core. It will, of course, be recognized that once 3,255,889 Patented June 14, 1966 the courses are entirely free from contact with the core, the uniform friction between one course and the next will eliminate the uncontrolled variables which are the primary cause of difficulty in manufacture.

It is an object of the present invention to make a simple and inexpensive modification of the core of a filter, such as has been discussed-above, whereby slippage of the strand, particularly at the point of reversal of direction of traverse direction, may be obviated.

A further object is to provide a filter element wherein the geometrical arrangement of superimposed layers of strand material is afforded anchorage on the core whereby the element may better resist axially imposed crushing loads.

Yet another object is to provide a convenient starting grip on the core for strand material being wound.

These and other objects and advantages will be more clearly understood from the following description con sidered in connection with the accompanying drawings wherein:

FIG. 1 is a side elevational view of wire mesh core showing one form of the present invention;

FIG. 2 is an end view of the construction shown in FIG. 1;

FIG. 3 is a side elevational view of a foraminous sheet metal core showing another form of the present invention;

FIG. 4 is an end view of the construction of FIG. 3;

FIG. 5 is an end view of the type of core shown in FIG. 3 with still another form of the present invention;

FIG. 6 is an end view of the structure of FIG. 5.

Referring to the drawings in detail, FIG. 1 shows a core, for a filter element, made of wire mesh. In commercial practice such cores are made of wire mesh. having about inch square openings. They are usually made either from flat woven material rolled up into the form of a cylinder and having a lap seam soldered or welded or they may be woven in tubular form and cut to length. In either event, the mesh material is most frequently dip tinned or galvanized which anchors the crossing points of the wires and affords a rigid structure. The wires usually are arranged to extend axially as at 20 and circumferentially as at 22. In the case of a common commercial construction, the core is about 1" diameter and has therefor a circumference of say 3 /8" with about twenty-five wires 20 running in an axial direction. In order to accomplish our purpose, we bend a number of these wires so that they extend radially outward about A; of an inch The as at 24. This is done at each end of the core. protrusions thus formed serve to anchor the strand material against axial movement, thereby insuring that the desired geometrical arrangement of the courses strand will not be deranged by slippage of its foundation. The positioning of such a strand is shown by broken lines 26. The foregoing arrangement is also shown in FIG. 2. It should be noted that while we show only a portion of the available wires turned outward radially they may be all so treated if desired. The arrangement delineated has, however, the advantage of affording a support which by extending axially beyond as at 20 beyond the anchor points 24 serves to prevent strand material being displaced radially inward of the core.

FIGURE 3 shows a core made of sheet metal indicated generally by the numeral 28 and having perforation 30 to provide passage of filtered fluid to the interior of the core. material by a plurality of slits 32' at the ends of the core and radially outwardly turning the tongue so formed. The notches 34 which are created by this operation are of use for engaging driving dogs on the spindle of the winding machine whereon the core is mounted for winding. Here also it will be seen that the anchors 32 are conveniently turned back axially of. the core so that as We here have created anchors 32 for the strand in the structure shown in FIG. 2, a support is afforded to prevent radially inward collapse of the strand material.

A modification of the structure of FIGS. 3 and 4 is shown in FIGS. 5 and 6, here as before the core 36 is preferably of sheet metal and has drainage perforations 38 but, in this case, we have substantially rectangular tongues 40 cut from the end portions of the core. It will be readily seen that the lancing slots 45 may be made during handling of the flat sheet metal from which the core is advantageously rolled. It will also be apparent that the tongues 40 may conveniently be forced into their operational radial position by engagement with suitable tongues or dogs in the driving spindle of the Winding machine which are thereby given a purchase or grip on the core in a manner very like the engagement of a toothed driving center used in wood turning. Other means of forming the tongues or protrusions on the core may be readily apparent.

In using cores such as are provided by our invention,

the length between the radially protruding anchors is made a fraction of an inch, say to less than the axial travel of the strand. By so doing we avoid cutting the strands on the anchors and the resulting structures are uniformly strong under axial loading, have well formed ends and few or no distorted or closed filtering passages.

It will be readily understood by those skilled in the art that while the anchors" provided, in say the structure of FIG. 1, will not anchor each course in contact with the core, the unanchored courses will have only a very limited slippage as they cross anchored courses, and such crossings have a sufiicently high frictional value to inhibit slipping.

It will thus be seen that the objects set forth above, and those made apparent from the preceding description, are efficiently attained. As various changes may be made in the form of construction, and arrangement of the parts herein without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted as illustrative and not in a limiting sense.

What we claim is:

1. A filter cartridge comprising a substantially cylindrical core having a plurality of radially extending protrusions at at least one end thereof and a plurality of helically wound crisscrossing courses of axially spaced continuous strand material, at least some of the first courses being anchored as wound about said protrusions.

2. A filter cartridge comprising a substantially cylindrical foraminous body having a plurality of integral radially extending protrusions at each end thereof and a plurality of helically wound crisscrossing courses of axially spaced continuous strand material, at least some of the first courses being anchored as wound about said protrusions.

3. A filter cartridge comprising a substantially cylindrical wire mesh body formed with a plurality of axially and circumferentially arranged wires, some of the axial wires being bent at their ends to form radially extending protrusions and a plurality of helically wound crisscrossing courses of axially spaced continuous strand material, at least some of the first courses being anchored as wound about said protrusions.

4. A filter cartridge comprising a substantially cylindrical forami-nous sheet metal body having a plurality of radially extending tongues cut and bent therefrom at its ends and a plurality of helically Wound crisscrossing courses of axially spaced continuous strand material, at least some of the first courses being anchored as wound about said protrusions.

References Cited by the Examiner UNITED STATES PATENTS 661,591 11/1900 Stukes.

673,398 5/1901 Keller et al. 2,035,758 3/1936 Pierce. 2,097,828 11/1937 Baldwin 210437 X 2,368,216 1/1945 Hasting 242176 X 2,770,426 11/1956 Sievers 210-457 2,980,354 4/1961 Mason 24218 FOREIGN PATENTS 1,114,777 12/ 1955 France.

618 11/ 1897 Great Britain. 406,303 2/1934 Great Britain. 488,532 12/1953 Italy.

REUBEN FRIEDMAN, Primary Examiner.

HERBERT L. MARTIN, Examiner.

F. W. MEDLEY, Assistant Examiner. 

2. A FILTER CARTRIDGE COMPRISING A SUBSTANTIALLY CYLINDRICAL FORAMINOUS BODY HAVING A PLURALITY OF INTEGRAL RADIALLY EXTENDING PROTRUSIONS AT EACH END THEREOF AND A PLURALITY OF HELICALLY WOUND CRISSCROSSING COURSES OF AXIALLY SPACED CONTINUOUS STRAND MATERIAL, AT LEST SOME OF THE FIRST COURSES BEING ANCHORED AS WOUND ABOUT SAID PROTRUSIONS. 